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Symbian C++ : Multipart/form-data

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Created: rathodavinash (27 Jun 2007)
Last edited: hamishwillee (26 Jul 2012)

The following code can be used to upload any file, image, text, video etc.. as a binary file to a server.

The HTTPEngine should have MHTTPDataSupplier as its parent class, as the following functions need to be implemented for the upload process

TBool GetNextDataPart(TPtrC8& aDataPart);
void ReleaseData();
TInt Reset();
TInt OverallDataSize();

The content-type for the post should be, hence add following lines to ClientEngine.h and declare variables under the CClientEngine class

_LIT8(KPostContentType, "multipart/form-data; boundary=AaB03x");
 
TBuf<255> iFileName;
HBufC8 *iPostDataImage;
HBufC16 *iResponseBuffer;
TBool iDataAvailable

In the MHFRunL the case EGotResponseBodyData should do this

MHTTPDataSupplier* dataSupplier = aTransaction.Response().Body();
TPtrC8 ptr;
iDataAvailable = dataSupplier->GetNextDataPart(ptr);
 
 
// Convert to 16-bit descriptor
HBufC* buf = HBufC::NewLC(ptr.Length());
buf->Des().Copy(ptr);
 
// Append to iResponseBuffer
if (iResponseBuffer==NULL)
{
iResponseBuffer = buf->AllocL();
}
else
{
iResponseBuffer = iResponseBuffer->ReAllocL(iResponseBuffer->Length()+buf->Length());
iResponseBuffer->Des().Append(*buf);
}
 
// Release buf
CleanupStack::PopAndDestroy(buf);
 
if(!iDataAvailable)
{
iRunning=EFalse;
iTransaction.Close();
}
else
{
dataSupplier->ReleaseData();
}


POST code Get the file you want to upload in binary format

RFs aFs;
User::LeaveIfError(aFs.Connect());
CleanupClosePushL(aFs);
 
RFile aFile;
 
User::LeaveIfError(aFile.Open(aFs, iFileName, EFileShareAny));
 
TInt aSize;
User::LeaveIfError(aFile.Size(aSize));
 
iPostDataImage = HBufC8::NewL(aSize);
TPtr8 aPtr = iPostDataImage->Des();
 
//Obviously we have to read in the data to the iPostDataImage (ray)
aFile.Read(0, aPtr, aSize);
 
aFile.Close();
aFs.Close();
CleanupStack::PopAndDestroy(&aFs);

Using EFileShareAny ensures that if the file can be opened by any other application. The file is read into iPostDataImage as a binary file.

Now create the upload format

_LIT8(KDataStart,"--AaB03x");
_LIT8(KCrlf,"\r\n");
_LIT8(KContent,"Content-Disposition: form-data; name='userfile'; filename='");
_LIT8(KFileCompletion,"'");
 
_LIT(KContent2,"Content-Type: image/gif");
_LIT(KContent3,"Content-Transfer-Encoding: binary");
_LIT8(KDataEnd,"--AaB03x--");
 
iPostData = HBufC8::NewL(650+aPtr.Length());
 
 
TPtr8 iPostDataPtr = iPostData->Des();
iPostDataPtr.Zero();
 
iPostDataPtr.Append(KCrlf);
iPostDataPtr.Append(KDataStart);
iPostDataPtr.Append(KCrlf);
iPostDataPtr.Append(KContent);
iPostDataPtr.Append(iFileName);
iPostDataPtr.Append(KFileCompletion);
iPostDataPtr.Append(KCrlf);
iPostDataPtr.Append(KContent2);
iPostDataPtr.Append(KCrlf);
iPostDataPtr.Append(KContent3);
iPostDataPtr.Append(KCrlf);
iPostDataPtr.Append(KCrlf);
iPostDataPtr.Append(aPtr); //the file in binary
iPostDataPtr.Append(KCrlf);
iPostDataPtr.Append(KDataEnd);
iPostDataPtr.Append(KCrlf);


Submit the transaction

RHTTPHeaders hdr = iTransaction.Request().GetHeaderCollection();
SetHeaderL(hdr, HTTP::EUserAgent, KUserAgent);
SetHeaderL(hdr, HTTP::EAccept, KAccept);
SetHeaderL(hdr, HTTP::EContentType, KPostContentType);
 
MHTTPDataSupplier* dataSupplier = this;
iTransaction.Request().SetBody(*dataSupplier);
 
iTransaction.SubmitL();


Implement DataSupplier functions

TBool CHTTPExampleEngine::GetNextDataPart(TPtrC8& aDataPart)
{
TBool retVal = EFalse;
aDataPart.Set(iPostData->Des());
retVal = (aDataPart.Length() == 0);
iDataAvailable=retVal;
return retVal;
}
 
TInt CHTTPExampleEngine::OverallDataSize()
{
if(iPostData)
return iPostData->Length();
else
return KErrNotFound ;
}
 
void CHTTPExampleEngine::ReleaseData()
{
if(iDataAvailable)
iTransaction.NotifyNewRequestBodyPartL();
}

Any binary file can be uploaded with this upload code.

This page was last modified on 26 July 2012, at 07:08.
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